As a test, can you format the card on your pc, copy data onto it, and then see how long it takes to copy it back off again? That should help narrow down a hardware issue vs a software/driver issue. I know you said it tests at 80MB/s, but I'm not sure how that test works. It may not be following the same mechanism that the OS would use to copy.

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yuxinhong

I Just did you what you said.formatted the card on pc.Copied the photos i took yesterday to the card - 1.14 GB speed was 42MB/sand when i download the exact same pictures to my PC, the speed where between 1.80-1.93MB/s

Are you dragging the files into your pc using drag asnd drop? That always seems to be much much slower than using software like lightroom to copy the images. Its not just pc cards, it can happen between pc's as well.

I downloaded images from my Sandisk 60 mb/sec card using the built-in card reader on my 3 year old Dell yesterday and noticed I was getting 25-27 mb/sec. Thats about what I expected for that setup. I just sold my two firewire 800 readers thinking I'll upgrade my pc to one with USB 3 this summer, and see if a usb 3 reader is faster. I'm waiting for windows 8, expecting some improved handling of SSD's as well. I'm not sure I am ready for a touch screen, and there will likely not be any high quality ones right away.

If I had D800 files that open to 200mb for editing, I'd be looking at a new one right now. Instead of my one 256 GB SSD, I'd need a couple 500GB SSD's running raid 0

Read and write speeds have a lot of factors why they can be slow. The file structure and file size. Lots of large files such as hd video can take longer since it needs the whole file to move to the next one. It could be the brand of card and media and finally just windows reporting. What is are you running?